body {
            max-width: 500px;
            margin: 0 auto;
            padding: 20px;
            font-family: Arial, sans-serif;
        }
        .todo-item {
            margin: 8px 0;
            padding: 8px;
            background: #f0f0f0;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        .completed {
            text-decoration: line-through;
            color: #888;
        }
        #todoInput {
            width: 70%;
            padding: 8px;
        }
        button {
            padding: 8px 12px;
            margin-left: 5px;
        }